Design and Construction of a Dual Powered Reverse Osmosis Based Mobile Water Treatment Plant for Military and Emergency Use

Abstract

A mobile water treatment plant was designed, constructed and tested to provide potable drinking water from almost all-natural water sources during military operations and emergency situations. The treatment plant was designed to fit into a Tata LPTA 713/32 military grade truck with payload capacity of 2500kg.In order to design a plant to treat water from different sources, several water treatment methods were analyzed including existing mobile water treatment plants in the Nigerian Defence Academy (NDA) to give a combination of treatment processes that effectively treat 2.16 m³ of water per day serving 505 cadets their daily water requirements with no time lapse per treatment cycle within a short period of time. The treatment flow process majorly involves the use of ion exchange unit, filtration units, water softening unit and reverse osmosis as the main treatment unit. Autodesk inventor software was used in the design and analysis of the locally constructed components. After the selection of the design process a reverse osmosis-based water treatment plant with 8 hours run time was constructed with water grade materials and processes. The treatment plant was tested using water samples from river Kaduna, water runoffs and pond from the Nigerian Defence Academy environs. The samples were tested at the Kaduna Water Board laboratory and the results obtained showed that the treatment unit was effective in removing all harmful microorganisms and adjusting all physiochemical properties of water to meet the Nigerian Standard for Drinking Water Quality. The filtration unit was capable of effectively reducing turbidity to the standard for all the water sample tested. The highest value of turbidity of raw water recorded was 1105 NTU and it was reduced to 4.05 NTU. The water softening units was effective for the removal of hardness to the desired standards; the highest value recorded at 208 mg/l was reduced to 60 mg/l. The treatment plant was also effective in stabilizing the PH of all the water samples to almost neutral as the PH values of all the treated water samples were between 6.8 and 7.10. The reverse osmosis unit was responsible for the removal of unwanted ions and heavy metals had high removal rate after testing except for Cadmium from river Kaduna sample which was 0.7408 ppm and reduced to 0.3407 ppm still higher than the recommended standard 0.03 ppm. At the end of this work it was observed that the water treatment plant was stable and consistent in treating water including the removal of heavy metals and that the efficiency of the removal of heavy metals can be improved by increasing the number of the reverse osmosis unit.